(The No. I of the Present Invention)
In recent years, treatment of waste plastics is becoming a social problem, and recycling of plastics material and biodegradable plastics are paid attention. An aliphatic polyester resin is one of materials which are largely desired owing to biodegradability.
As one of the aliphatic polyester resins which are industrially produced, a polycaprolactone is known. A polycaprolactone having a low molecular weight is an important material as a raw material for a polyurethane, a paint, and a coating agent. A polycaprolactone having a high molecular weight is employed as a molded article such as a compost bag, fishing lines, tees for golf, and a hot-melt adhesive, etc. owing to biodegradability.
Further, the aliphatic polyester has been widely employed as a preferred material also in uses such as a use for molding various portions of human body and a use by fitting to human body. For example, a gyps for medical care (JP-A-58081042 Official Gazette) and a face mask for irradiating radiation rays (JP-A-60215018 Official Gazette) have been known.
It is known that although such the aliphatic polyester has a peculiar thermally-decomposing property, hydrolyzability, and biodegradability, etc., respectively, in the case of the uses, thermally-decomposing property, hydrolyzability, and biodegradability, decomposition or degradation rate become important depending upon the uses thereof, accordingly, their properties can be modified by various copolymerization.
For example, the thermally-decomposing property, hydrolyzability, and biodegradability of the aliphatic polyesters are controlled by a copolymerization of a lactone with a lactide, a copolymerization of a lactone with a glycolide, a copolymerization of a lactone with a carbonate, a copolymerization of a lactone with a cyclic ester, a copolymerization of a lactone with a lactam and, or modification of composition ratio, etc.
Still further, in a polycondensation type polyester, it is tried to highly-polymerize by an isocyanate compound (JP-A-04189823 and JP-A-05178955 Official Gazettes). However, since a polymer having a sufficiently high molecular weight can be obtained without a crosslinking reaction in the aliphatic polyester which is obtained by the ring-opening polymerization such as in the present invention, there was not investigated a reaction with an isocyanate compound, etc.
In the case of controlling the thermally-decomposing property, hydrolyzability, and biodegradability of the aliphatic polyesters, although there can be obtained a polymer having a desired thermally-decomposing property, hydrolyzability, and biodegradability by copolymerization, there is a problem that the copolymerization also affects to various other physical properties, resulting in that there cannot be obtained a target polymer.
(The No. II of the Present Invention)
Hitherto, for the purpose of manifestation of a fertilizing effect depending upon growth of farm products, there have been developed various fertilizing effect-controllable fertilizers.
Particularly, there have been disclosed and commercially-supplied a particle-state fertilizer in which a coating material is coated on the surface. As described in JP-B-95000505 Official Gazette, there have been proposed various fertilizing effect-controllable fertilizers in, for example, U.S. Pat. No. 3,295,950, JP-B-65028927, JP-B-69028457, GB Patent 815829, JP-B-62015832 and JP-B-67013681 Official Gazettes. However, it is taught that it is difficult to adjust an elution rate of fertilizing components in all the fertilizing effect-controllable fertilizers.
On the other hand, JP-B-85021952 and JP-B-85003040 Official Gazettes disclose a method for forming a thin layer in which there is employed a coating material primarily containing a polyolefin, and in the case of coating the surface of particle-state fertilizers, a hot air is blown to dry together with spraying a solution of the coating material over the particle-state fertilizers. It is taught that the method is characterized in that an elution rate of the fertilizers can be controlled, and the above-described method is widely put into practice, in which a thin layer is formed over the surface of the particle-state fertilizers.
Further, JP-B-85003040 and JP-A-55901672 Official Gazettes, etc. show that a function for controlling elution is maintained by dispersing inorganic powders such as talc and sulphur into a thin layer of the polyolefin-based resin and, at the same time, there is accelerated the degradation or decomposition of residual thin layer after elution.
In the particle-state fertilizers which have been conventionally proposed, the coating layers do not cause degradation or decomposition, and even though those caused the degradation, those remain in soil, resulting in that it is anxious that those produce pollution in the growth of farm products, soil circumstances, and water for irrigation and river around fields.
From that reason, there has been intensively desired a particle-state fertilizer in which a thin layer has degradability and a duration period of a fertilizing effect can be controlled.
In such the degradable thin layer, degradability means degradation by light, oxygen, and microorganisms, etc.
Particularly, in the conventional particle-state fertilizer coated, it is difficult to control the elution rate of fertilizing components, and there has been a drawback that the fertilizing period is apt to be readily affected by circumstances such as weather and soil. Further, it is pointed that the thin layer after elution of the fertilizing components remain in soil over a long time of period without degradation.
For that reason, utilization of biodegradable resins has been often tried and, for example, JP-A-07033576 Official Gazette states a combination of a polycaprolactone, a polylactic acid, or an aliphatic polyester compound with cellulose derivatives, low molecular weight polyethylenes, and paraffins, etc. However, since the polycaprolactone to be employed in the case has a melting point of 60° C., blocking is occasionally caused in transport or storage of products.
Further, the above-described JP-B-95000505 also likewise discloses particle-state fertilizers coated by a polycaprolactone.
However, in the coating material such as the polycaprolactone and polylactic acid, since degradation of the coating materials is too quick, those are not preferred in the case of employing as a gradually-dischargeable fertilizer.
(The No. III of the Present Invention)
In addition to the above-described problems relating to the coating materials, since the polylactic acid and the aliphatic polyester have a low solubility to solvents, it is difficult to put into practice, resulting in being not sufficiently satisfied.
Further, in JP-A-11116371 Official Gazette, there is proposed the use of a cellulose acetate having a low substitution degree which is poor in solubility and, in the case of employing coating for a particle-state fertilizer, trichloroethylene and tetrahydrofran are employed as solvents. Accordingly, handling and price of the solvents have been problematic.
(The IV of the Present Invention>
A marking film means a film which is stuck on wall surface of transport vehicles, buildings, and electric-light poles, etc. in which a printed and ink layer are formed on one surface of a base film for (wappen) to prepare various patterns, and a pressure sensitive adhesive layer is formed on other surface, which is employed by sticking it at surface of a large-size outdoor advertisements, road signs, signboards on streets, company trade names, etc., and clothes, daily necessaries, and toys, etc. It is pais attention owing to effectively setting by only sticking in place of a method for individually coating a paint. As a base film which has been conventionally employed for a marking film, although a polyester film and a polyurethane film are also known a little, a film made from a polyvinylchloride-based resin is typical in view of weatherability, total properties in use (that is, characteristics depending upon elasticity, a readily sticking property onto a curved surface, a readily sticking property of a curved film onto a plain surface, and bulkiness of a film), and costs.
The vinylchloride-based resin is excellent in various properties such as physical properties, weatherability, film formability and printing applicability, and which has been preferably employed as a base film material for the marking film.
In the vinylchloride-based resin which is a typical example as described above, polymerization degree is preferably 300-2000, and more preferably 600-1500, and a polyvinylchloride homopolymer resin or a copolymer resin of vinylchloride monomer with various monomers such as an olefin-based, diene-based, halogenated vinyl-based, (meth)acrylic ester-based, vinyl ester-based, vinyl ether-based, and styrene-based monomers.
Incidentally, as one example of the marking film and use modes thereof, there is exemplified a rolled marking film in which there is prepared a base film having 50 μm for the marking film of the vinylchloride resin cast by a plastisol method, and desired durable patterns, etc. are printed on one surface, and optionally, a clear ink is over-printed to give a high durability and, an acrylic-based pressure sensitive adhesive is coated in the thickness of approximately 30 μm on another surface, and optionally, a releasing film is laminated as a backing film. It is stuck on surface of the body of a car, etc., stripping off the releasing film at a sticking place after forming a cutting mark line in order to cut it into a desired shape by a hand-cut, computerized machine-cut, and punching cut.
In the meantime, it is reported that the above-described polyvinylchloride-based resin which has been preferably employed has a large possibility that it produces harmful substances such as dioxine during burning and dumping, and as a result, a research for substitute resin materials is in progress.
As one of the substitute resins, there are paid attention a cellulose ester, for example, a cellulose acetate, a cellulose acetate butylate, a cellulose acetate propionate which are all a cellulose derivative, and which satisfy a variety of properties to be required such as excellent toughness, glossiness, transparency, oil resistance, and weatherability as a resin for the marking film.
However, if those are thermally melted alone, discoloration and decomposition are simultaneously caused and, further, even though there is applied a so-called block method in which the above-described cellulose derivatives are dissolved, kneaded, compressed, and molded to prepare a sheet, there cannot be obtained a resin having an excellent fluidity in heating and a plasticizing property without the addition of a plasticizer. In the case, as a plasticizer, there are employed a phthalate (for example, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butylbenzyl phthalate, and ethylphthalyl phthalate ethyl glycolate, etc.), a trimeritate (for example, trimethyl trimeritate, triethyl trimeritate, and 2-ethylhexyl azelate, etc.), a normal phosphate (for example, tributyl phosphate, cresyl diphenyl phosphate, and 2-ethylhexyl diphenyl phosphate, etc.), and a licinolate (for example, methyl acetyl licinolate), etc.
However, the cellulose esters containing the plasticizers have a problem that a softening point becomes too low.
Further, since the cellulose derivatives such as the cellulose esters are usually strong in polarity, there must be selected a plasticizer having a strong polarity. However, as a plasticizer which satisfies wide range properties, compatibility, a plasticizing effect, a high transparency, non-volatility, and a non-migrating property, a conventionally known plasticizer having a low molecular weight is known alone, and the plasticizer is apt to readily volatile during molding or after molding. Accordingly, it has a problem that a working circumstance during molding becomes worse and dimensional stability lowers in a molded article.
Further, the plasticizer migrates toward a pressure sensitive adhesive layer or a printing surface in the marking film, resulting in that an adhesive power lowers in the former and a stain by dust sticking is caused in the latter.
As a result, there is limited the use of a low molecular weight plasticizer for the cellulose derivatives such as the cellulose esters, etc., and it is an existing circumstance that it obstructs an enlargement of uses for a film or a sheet made by the materials, particularly, the use for the marking film, etc.
In order to overcome the limitation in use of the low molecular weight plasticizer, for example, JP-B-68016305 Official Gazette discloses a technology in which there is added a high molecular weight plasticizer which is a polyester having an average molecular weight of 700-4000 obtained from a cellulose acetate which is a fatty acid cellulose ester, a glycol, and an aliphatic dibasic acid. The plasticizer is excellent in compatibility with a cellulose acetate having an acetylated degree of not less than 52% (substitution degree of not more than 2.2).
Further, U.S. Pat. No. 3,813,81 Specification discloses a technology in which a polymer from a cyclic monomer such as e-caprolactone is added to a cellulose acetate (substitution degree of 2.5) which is a cellulose ester.
Still further, U.S. Pat. No. 4,731,122 Specification discloses a thermoplastic resin composition in which a cellulose acetate butylate and a cellulose acetate contain tributyl citrate, triethyl citrate, and a polyethylene glycol.
However, the above-described high molecular weight plasticizer is still insufficient in compatibility with the cellulose ester and, particularly, in the case that it is applied to a cellulose ester having a low substitution degree, it is difficult to prevent that it bleeds out of a molded article, and it volatilizes from a molded article, resulting in that it adversely affects to physical properties such as an outer appearance of a molded article which includes a decrease of transparency by phase separation, and a decrease of a plasticizing effect.
(The No. V of the Present Invention)
As a heat-transfer method for a picture image, various methods have been conventionally known and, for example, there is proposed a method in which a variety of full-color picture images are thermally formed on a picture image recording sheet by bringing into contact a heat-transferable sheet in which a recording agent such as a sublimatable dye is carried on a base material sheet (for example, a polyester film, etc.) with a picture image recording sheet having a dye receiving layer on a material (for example, paper and plastic film, etc.) to be transferred which is capable of dying by using a sublimatable dye.
In the method, a thermal head of a printer is employed as a heating means, and a great many of color dots including 3 or 4 colors are transferred to a picture image recording sheet by heating for an exceedingly short time of period, resulting in that a variety of full-color picture images are thermally reappeared on a recording sheet. Thus-formed picture image is very distinct because a dye is employed as a coloring material, and it is excellent in transparency. Accordingly, a picture image obtained is excellent in repeatability of a medium color and a contrast, and there can be formed a high-quality picture image which is much for a full-color photograph.
In the heat transfer method, there is important not only a construction of a heat-transferable sheet but also a construction of a picture image recording sheet. As the picture image recording sheet by a heat-sensitive transfer, there has been known a sheet in which there is formed a picture image recording layer using, for example, a polyester-based resin, a vinyl resin containing halogens such as a polyvinyl chloride-based resin, a polycarbonate-based resin, a polyvinyl butylal-based resin, an acrylic-based resin, a cellulose-based resin, an olefin-based resin, and a styrene-based resin, etc.
In such the picture image recording sheet by a heat-sensitive transfer, as a means by which a dyeing property becomes excellent in the sublimatable dye to be transferred, there is a method for forming a dye receiving layer using a resin having an excellent dyeing property.
For example, JP-A-62211195 Official Gazette proposes a picture image recording sheet by a heat-sensitive transfer in which a picture image recording layer having a high surface smoothness is formed by a mixture containing a pigment and a resin which can be readily dyed such as a polyester, an epoxy resin, and a polystyrene. In the JP, it is described that the resin which can be readily dyed may be a water soluble-type and an emulsion type one.
However, the resin which can be readily dyed by a dye has a low softening point and, in the case that a dye-receiving layer is formed in the heat transferable picture image recording sheet using such the resins, the dye-receiving layer and the heat-transfer sheet are adhered to each other by heat of a thermal head during forming a picture image and, when those are stripped from each other, there is caused a problem (a so-called abnormal transfer) that a dye layer in the heat-transfer sheet is entirely transferred onto the picture image recording sheet by fusing each other. Also, as a method for improving a dye-affinity in a dye, there are a method in which a plasticizer is contained in the dye-receiving layer and a method for improving a diffusible property in the dye of heat-transfer. However, a picture image formed blots and storage property is low.
JP-A-62222895 Official Gazette discloses a picture image recording medium in which a dyeing layer in the picture image recording medium which is a sublimatable heat-sensitive type one contains an acrylic-based polymer and a surface improver having a fluorine-based or silicone-based graft or block structure.
JP-A-06024152 Official Gazette proposes that a dye receiving layer in a picture image recording medium which is a sublimatable heat-sensitive type one is formed by a composite polymeric water-based based dispersion in which a core-shell structure is formed by a polymer of a copolyester resin having at least one polar group with a copolymerizable unsaturated compound. However, in the picture image recording medium, it is difficult to improve a coloring concentration and clearness of a picture image while elevating a strippability from a heat-transfer sheet. As described above, when improving a dye-affinity of a dye receiving layer, a strippability lowers and, when intending to improve the strippability and storage stability by forming a picture image recording layer using a resin in which a dye absorbed is not apt to migrate through the dye absorbing layer, dye-affinity of the dye becomes lower, resulting in that there cannot be formed a picture image having a high concentration and high clearness.
(The Sixth Aspect of the Present Invention)
In a heat-transfer recording method, a printing is recorded on a paper to be transferred as follows. First of all, the paper to be transferred is brought into contact with a heat-transferable ink layer in a heat-transfer recording medium composed of a substrate and the heat-transferable ink layer which is arranged on the surface of the substrate under pressure, and then, a thermal head is brought into contact with an opposite surface (back surface) of the heat-transferable ink layer in the substrate. Subsequently, the thermal head is heated by supplying a pulse-state signal current into the thermal head and, the heat-transferable ink layer is melted or sublimated by heating.
In a thermally melt type transfer recording method, a picture image is recorded as follows. In the case of black painting, there is employed a heat-transfer recording medium in which carbon black is added to an ink layer and, in the case of color printing, a heat-transfer recording medium composed of three primary colors such as yellow, magenta, and cyan are separately prepared and, the three primary colors are transferred in order onto the same paper to be transferred, respectively.
On the other hand, in a sublimation type heat-transfer method, a contrast-controlled printing can be readily conducted while controlling the amount of an ink which sublimates by a heat amount from a thermal head. In order to print a picture image with a high concentration, input voltage is elevated or input time of period of an electric current pulse is lengthened and, in order to print a picture image with a low concentration, input voltage is lowered or input time of period of an electric current pulse is shortened. A color printing can be conducted by the same method as in the thermally-melting type method, and a color printing having a high contrast can be conducted by changing quantity of heat on the thermal head.
In the mean time, as a substrate for a thermal melting or a sublimation type heat-transferable recording medium, there has been conventionally employed a plastic film such as a polyethylene terephthalate (PET). Herein, the plastic film such as the PET occasionally fusedly-adheres to a thermal head by melting in a contact portion to the thermal head because of heat of the thermal head during transferring, resulting in that the recording medium cannot become transferred with a stable speed.
The phenomenon (a sticking phenomenon) not only remarkably lowers a printing quality but also causes a significant noise when the fusedly-adhered film is stripped off from the thermal head, and allows to stop transferring of the recording medium, or occasionally causes a fracture of the substrate. In order to prevent the sticking phenomenon, there are proposed a variety of methods for forming a thermally resistible protecting layer at one surface (a surface bringing into contact with the thermal head which is an opposite side of a heat-transferable ink layer) in the substrate.
For example, JP-A-55007467 and JP-A-63172688 Official Gazettes propose that there is set up a heat-resistible protecting layer composed of a silicone resin, an epoxy resin, a melamine resin, a phenol resin, fluorine resin, a polyimide resin, a polyamide resin or a cellulose resin at one surface of a substrate.
Further, JP-A-60201989 Official Gazette proposes that there is set up a heat-resistible protecting layer composed of an aromatic polyamide, and JP-A-60201989 Official Gazette proposes a heat-resistible protecting layer composed of an aromatic polysulphone-based resin, respectively. However, the heat-resistible protecting layer is insufficient for protecting the sticking phenomenon and, in the case that the heat-transferable recording medium is stored in a rolled state, there is caused a so-called blocking phenomenon that the heat-resistible protecting layer adheres to a heat-transferable ink layer. By occurrence of the blocking phenomenon, the heat-transferable recording medium in a rolled state becomes not occasionally smoothly transferred, components in the ink layer which migrate and adhere to the heat-resistible protecting layer adhere to a heating body in the thermal head and surroundings thereof, resulting in that printing quality is remarkably lowered.
Still further, JP-A-61143195 Official Gazette proposes that there is set up a back surface layer (a heat-resistible protecting layer) composed of a silicone-graft or block acrylic-based copolymer. The back surface layer composed of the silicone-graft or block acrylic-based copolymer is excellent in a slipping property and prevents a sticking phenomenon, and it is excellent in heat resistance and a blocking resistance. However, since the silicone-graft or block acrylic-based copolymer is poor in a film formability, the back surface layer composed of the copolymer is shaved by the thermal head when continuously printing and, components of the back surface layer adhere to the heating body of the thermal head and circumstances thereof, printing quality lowers as well as in the case of the occurrence of the blocking phenomenon.
For that reason, there is a drawback that the thermal head must be often cleared in order to obtain an excellent printing quality.
JP-A-01221281 Official Gazette proposes that there is set up a heat-resistible protecting layer in which a silicone oil added to an ethyl cellulose resin. However, as well as a method (JP-A-57129789 Official Gazette) in which there is set up a resin layer in which there is added a surface active agent which is solid or semi-solid at ordinary temperatures, there is a drawback that additives such as the silicone oil or the surface active agent migrate toward an ink layer, and there are caused unevenness of transferring and lack of a picture image, resulting in that printing quality is remarkably lowered.
JP-A-01234292 Official Gazette describes that there is set up a heat-resistible protecting layer in which a silicone oil is added to a cellulose ester resin containing acetate group or the ester resin containing a silicone oil, and JP-A-07172076 Official Gazette describes that there is set up a protecting layer in which waxes, higher fatty acid amides, or an ester are added to an acrylic resin, a polyester resin, and a cellulose derivative, etc. However, there are still remained an inconvenience such as the above-described sticking phenomenon and blocking phenomenon, and an inconvenience such as the unevenness of transferring and a lack of a picture image by migration of the additives toward the ink layer.
JP-A-06270561 Official Gazette proposes that there is employed a cellulose modified polymer in which a cellulose and/or a cellulose derivative are a main polymer and a copolymer of a reactive silicone oil with a vinyl monomer is a branch polymer as a protecting layer. As a method for introducing the vinyl monomer into the cellulose derivative, two methods are proposed. One is a method in which a polymerization of the vinyl monomer is initiated by pulling out an active hydrogen of the cellulose, and another is a method in which vinyl groups are introduced into the cellulose derivative, followed by allowing to polymerize with other vinyl monomers. Further, there are proposed two methods for introducing a reactive silicone oil, and one is a method in which a reactive silicone oil having vinyl group is allowed to react with other vinyl monomers and the above-described cellulose derivative.
Another is a method in which a reactive silicone oil having a hydroxyl group or an epoxy group at a terminal is combined with an isocyanate compound having vinyl group to introduce a double bond, followed by allowing to react with other vinyl monomers and the above-described cellulose derivative. As described above, the method for the preparation of the cellulose-modified derivative is complicated in the JP-A-06270561 Official Gazette and, productivity is poor, and the monomers to be employed are expensive. Accordingly, the methods are not preferred because of a viewpoint of costs.
As described hereinabove, it is an existing circumstance that as the heat-resistible protecting layer for the heat-transferable recording medium, although there have been proposed various materials until now, there is occasionally caused a decline of a printing quality by occurrence of a worse transferring and an abrasion of a thermal head, or occurrence of a fracture, etc. in a substrate and, moreover, a blocking resistance and thermal head stain resistance, etc. are insufficient, and satisfied protecting layers are not found out.
(The No. VII of the Present Invention)
Heretofore, as a method for coating a conductive coating, there has been usually carried out a method in which a conductive coating composition is coated on a nonconductive material to be coated such as inorganic materials and plastics, and after giving conductivity to the surface of the nonconductive material to be coated, and then, a finishing-coating composition is coated by static coating.
As the conductive coating composition, there has been known, for example, a mixture in which an amino alkyd-based resin and an amino acrylic-based resin, etc. are mixed and dispersed with, for example, powdered metals such as a stainless steel, tin, copper, ad aluminum; a metal oxide such as zinc oxide, conductive fillers such as a titanium dioxide-coated mica, a silicone, and cobalt sulphide, which are a conductive pigment.
However, since the powdered metals themselves have small electric resistance, although the use amount is small, those are not practical because of a high price. Further, there is a drawback that since those have large specific gravity, those are separated from resin components and sink in a bottom of a vessel, and those aggregate, and those cause hard-caking during a long term storage, it becomes difficult to disperse again in an original state in spite of agitating, resulting in that there is formed a coating layer containing a small amount of powdered metals, and conductivity becomes worse in a coating layer.
On the other hand, the metal oxides have a drawback that since the metal oxides themselves have a larger electric resistance compared to powdered metals, in the case of intending to obtain a coating layer having equal conductivity to the powdered metals, use amount becomes large, resulting in that there become worse storage stability and physical properties in a coating composition.
Further, it is difficult to obtain a coating layer having an excellent conductivity by a small amount even in the conductive fillers.
Still further, it has been known that conductivity can be elevated by conductive pigments such as a conductive carbon and a scaly graphite which are a carbon-based pigment.
Although the conductive carbon is usually mixed and dispersed into a coating using a dispersing machine such as a ball mill or a sand mill, it has a drawback that when the conductive carbon is dispersed until becoming a state of primary particles in the case of dispersing, conductivity of the coating layer becomes poor by formation of a coating layer in which conductive carbon particles do not sufficiently bring into contact each other, and in the case of increasing the mixing amount of the conductive carbon in order to elevate the conductivity, physical properties become poor in the coating layer. On the other hand, in the case that aggregated particles of the conductive carbon are placed in a large amount without sufficiently dispersing the particles of the conductive carbon, it has a drawback that a storage stability becomes worse in the coating composition, and an outer appearance of the coating layer also becomes poor after finishing.
Also, although the scaly graphite can form a coating layer having an excellent conductivity even in the case of the smaller use amount compared to the conductive carbon, it has a drawback that it is poor in, particularly, an adhering property to a plastic material to be coated and adhesion to an over coating layer.
(The No. VIII of the Present Invention)
Heretofore, in the case of coating or repairing industrial machines, buildings, structures, furniture, and cars, etc., an acrylic urethane coating has been mainly employed in view of durability, a finishing property, and weatherability.
The coating can form a coating layer having excellent properties as an ordinary temperature-curable type one.
However, since the acrylic urethane coating is usually a two-liquid type, it must be employed within a fixed time of period, resulting in that it has a problem in coating workability. Further, in the coating, since a polyisocyanate compound having a relatively low molecular weight is employed as a curing agent, it includes a problem of toxicity and an irritating property by vapor thereof when coating it at a coating site.
On the other hand, there have been conventionally proposed a variety of moisture-curable type coatings using isocyanate group which is a single liquid type. For example, JP-A-56118409 and JP-A-64075578 Official Gazettes disclose coatings using a copolymer containing isocyanate group, whereby, an improvement is attained in view of coating workability and, safeness and public health.
However, the coatings do not attain to properties of the two liquid type acrylic urethane coatings in view of dryability and physical properties which are particularly desired as the ordinary temperature-curable type coatings.
(The No. IX of the Present Invention)
In recent years, treatments of waste plastics are becoming a large social problem, and a biodegradable plastics has been largely paid attention. An aliphatic polyester is one of materials which are largely expected owing to a high biodegradability compared to other synthetic resin.
As the aliphatic polyesters which are industrially manufactured, there can be enumerated, for example, a polylactic acid which is an aliphatic polyester having a high melting point, a polyhydroxy butyrate, a polyglycol acid, and a polycaprolactone which is an aliphatic polyester having a low melting point, etc.
The polylactic acid having a high molecular weight and the polycaprolactone have been employed as medical uses such as surgical strings, medical gyps (JP-A-58081042 Official Gazette), and a face mask for irradiating radiation rays (JP-A-60215018 Official Gazette), and compost bags, fishing lines, tees for golfing and a variety of molded articles, and a hot-melt adhesive, etc., which are usual applications.
However, the aliphatic polyester having a high melting point, which is typified by by the polylactic acid (a melting point of approximately 175° C.), the polyhydroxy butylate, and the polyglycol acid, etc., has a drawback of being hard and brittle because of high crystallinity and rigid molecular structure, and the polyester typified by the polycaprolactone includes a practical problem because of a low melting point.
Therefore, there have been conventionally investigated a method in which a plasticizer is added to a polyester having a high melting point (JP-A-04335060 Official Gazette) and a mere copolymer of a polyester having a high melting point with a polyester having a low melting point (JP-A-07053685 and JP-A-07316271 Official Gazettes), those are not still sufficient from a viewpoint of practical uses.
That is, in the method in which the plasticizer is employed, there become largely problematic a toxicity and low biodegradability of the plasticizer itself, bleed out during molding, and staining of a mold, etc. In a lactide/ε-caprolactone copolymer having a very long chain which is a completely block type as described in the JP-A-07316271 Official Gazette, there is not almost improved a drawback of being hard and brittle, it is exceedingly limited in practical uses. Likewise, as described in the JP-A-07053685 Official Gazette, in the case that the monomer formulation of the lactide/ε-caprolactone is merely only regulated without any consideration of an average continuous chain length of constructing monomer units, it is clear that there cannot be always prepared a copolymer having a desired physical properties.
On the other hand, as a method for the preparation of a lactide/ε-caprolactone copolymer having a controlled average continuous chain, there is reported a method (Polymer Bulletin 25, 335-341 (1991), Macromol. Chem. 194, 907-912 (1993)) in which an average continuous chain length of respective units is controlled by changing reaction temperature and catalysts. However, in the case of changing the reaction temperature and catalysts, there are not avoidable fluctuations of preparation conditions and, in the case of consideration of a production change among several grades using an identical production apparatus, it is clear that it becomes a factor of a remarkable decline in productivity.
Accordingly, it is virtually difficult that conventionally known methods are applied to an actual production in an industrial fashion.